Acquired Immune Deficiency Syndrome (AIDS) is the clinical manifestation of the apparent infection of CD4 helper T-cells and other cell targets by human immunodeficiency virus (HIV), also previously referred to as human T-lymphotropic virus type III (HTLV-III), Lymphoadenopathy-associated virus (LAV), or AIDS-related virus (ARV) (hereinafter collectively "HIV"). AIDS is a transmissible deficiency of cellular immunity characterized by opportunistic infections and certain malignancies. A similar disease, AIDS-related complex (ARC), shares many of the epidemiological features and immune abnormalities with AIDS, and often precedes the clinical manifestations of AIDS.
A vaccine against AIDS and/or ARC is an ideal prophylactic treatment for preventing the delibilitating effects of infection by HIV. Applicants have discovered an immunogen useful for such a vaccine. The immunogen is a 5' fusion of the HBsAg (Hepatitis B surface antigen) and one or more HIV envelope fragments.
Many of the details of the genetic function and virion structure of HIV have not yet been elucidated. However, certain general features have emerged. An RNA virus with a genome totaling about 9 kilobases (kb), the nucleotide sequence of HIV contains seven major open reading frames (ORFs) corresponding to the gag, pol and env, vif, tat, rev, and nef genes. The genes gag, pol and env code respectively for core subunits, viral enzymes such as reverse transcriptase or protease, and outer surface (envelope) subunits. The gene vif codes for a viral infectivity factor, which is a protein involved with enhancement of cell-to-cell transmission of virions without affecting the budding process. The gene tat codes for a small protein required for viral infectivity, but its mechanism of action is not clear. The gene rev regulates expression of the viral proteins of gag, pol and env genes, possibly by facilitating transport of incompletely spliced RNA. The nef gene codes for a viral protein found in the cell cytoplasm, and it may modulate the host cellular signaling system and serve as a transciptional silencer. Terminal repeats in the nucleotide sequence are common to many retroviruses such as HIV and are required for viral replication and integration into the host chromosome. More recent discussions of the general nature of HIV genomic structure, replication and regulation are found in Ratner, L. et al. "Human T-Lymphotropic Retroviruses," in O'Brien, S. J. (ed.) Genetic Maps 1987 Cold Spring Harbor 1987 pp. 124-129; Franchini, G. et al., Nature 328, 539 (1987); Varmus, H. Genes & Dev 2, 1055 (1988).
Attempts to develop a vaccine to prevent infection with HIV generally have concentrated on the elicitation of specific virus-neutralizing antibodies. A region of the HIV surface coat protein (gp120) which is involved in the generation of such antibodies has been defined [Goudsmit et al., Proc. Natl. Acad. Sci. USA 85, 4478 (1988); Ho et al., J. Virol. 61, 2024 (1987); Matsushita et al., J. Virol. 62, 2107 (1988); Palker et al., Proc. Natl. Acad. Sci. USA 85, 1932 (1988); Rusche et al., Proc. Natl. Acad. Sci. USA 85, 3198 (1988); Skinner et al., J. Virol. 62, 4195 (1988)]. However, attempts to use the intact viral coat protein or portions thereof to readily elicit significant levels of neutralizing antibodies have proven unsuccessful [Berman et al., Proc. Natl. Acad. Sci. USA 85, 5200 (1988); Hu et al., Nature 328, 721 (1987); Lasky et al., Science 233, 209 (1986); Putney et al., Science 234, 1392 (1986); Robey et al., Proc. Natl. Acad. Sci. USA 83, 7023 (1986); Rusche et al., Proc. Natl. Acad. Sci. USA 84, 6924 (1987)].
Applicants of the present invention have constructed novel vectors for the synthesis of novel recombinant fusion protein (RFP) wherein the RFP is an amino-terminal fusion of HIV envelope protein fragment sequence with HBsAg at the carboxy-terminal end. The fusions of the present invention are capable of exhibiting a neutralizing antibody response, which is thought to be a critical requirement of vaccine efficacy. The RFP's of the present invention are useful as vaccines against AIDS and/ or ARC, as well as against hepatitis.
The present application is drawn to genes for novel RFP's, their cloning and expression vectors, expression systems for RFP, as well as processes for making these constructions and for purifying the resulting RFP. The present application also encompasses formulations of RFP suitable as vaccines against AIDS and/or ARC, as well as hepatitis, whether or not in combination with other AIDS antivirals, immunomodulators, antibiotics or vaccines. Such an invention provides an immunogen useful for inducing antibodies for passive protection or treatment of AIDS and/or ARC. The immunogen and its specific antibodies are useful diagnostic reagents.
One advantage of the RFP of the present invention is that it provides a vaccine for simultaneous protection against hepatitis and AIDS. The particular hepatitis disease indicated here are those caused by hepatitis B virus (HBV).
AIDS is a disease caused by a virus (HIV) with a unique collection of attributes. HIV itself targets the immune system; it possesses a reverse transcriptase capable of turning out highly mutated progeny; it is sequestered from the immune system and it has a hypervariable surface in the env region. See, e.g. Hilleman, M. R., Vaccine 6, 175 (1988); Barnes, D. M., Science 240, 719 (1988). In view of these attributes, it was neither anticipated nor expected that the fusions of this invention would be useful as AIDS vaccines.